By 2100, human activities will add 310 gigatons of carbon to the world’s oceans, a threshold that could ultimately lead to mass extinction

Increasing carbon pressure on oceans could turn Earth’s sixth mass extinction a reality by year 2100, a study by the Massachusetts Institute of Technology (MIT) has claimed. The study, ‘Thresholds of catastrophe in the Earth system’, conducted by Daniel H. Rothman, professor of geophysics at MIT’s Department of Earth, Atmospheric and Planetary Sciences, contends that human activities will add 310 gigatons of carbon to the world’s oceans, a threshold that would lead to an unstable environment and ultimately, to mass extinction.

In the study, published in the international scientific journal Science Advances, Rothman uses a mathematical formula based on the rate and magnitude of change in the carbon cycle. The study analysed 31 carbon isotopic events during the past 542 million years which led to significant change in Earth’s carbon cycle. It said that in the past 540 million years, the Earth has seen five mass extinction events.

Rothman then identified “thresholds of catastrophe” in the carbon cycle that, if exceeded, could lead to mass extinction. According to the study, that threshold is about 310 gigatons, which is roughly equivalent to the amount of carbon that human activities would have added to the world’s oceans by the year 2100.

“The modern critical size for the marine carbon cycle is roughly similar to the mass of carbon that human activities will likely have added to the oceans by the year 2100,” Rothman says in his study.

Rothman said this isn’t to say that a catastrophe will happen tomorrow. “It’s saying that, if left unchecked, the carbon cycle would move into a realm which would be no longer stable, and would behave in a way that would be difficult to predict. In the geologic past, this type of behaviour is associated with mass extinction.”

In July, a study published in the Proceedings of the National Academy of Sciences, a US scientific journal, claimed that the sixth mass extinction of species is underway thanks to factors such as overpopulation and overconsumption, and there is little time left for effective action.

It had said that as much as half of the number of animals that once shared the Earth with humans are already gone, and that the next two decades would see more powerful assaults on biodiversity.

Rothman said that his study highlights the imperative of controlling carbon emissions.